In the prior art, seat angle adjusting mechanism can be generally divided into two kinds: plate spring adjusting mechanism on the principle of detent and ratchet; and gear-driven adjusting mechanism on the principle of planetary gear transmission. The seat angle adjusting mechanisms disclosed in the Chinese utility model publications No. CN2,358,759, CN2,494,632, CN257,768 and CN2,590,784 are plate spring adjusting mechanisms on the principle of detent and ratchet. Continuous adjustment as well as electrical adjustment cannot be implemented in these four core transmission means because of the limitation rooted in their structures.
Gear-driven adjusting assemblies for continuous adjustment of seat angle in the prior art includes: adjusting mechanisms of double inner-meshed gear transmission and adjusting mechanisms of single inner-meshed gear transmission.
The seat angle adjusting mechanisms disclosed in the Chinese utility model publications No. CN2,193,087 and CN2,696,412 are gear-driven adjusting mechanisms adopting double inner-meshed gear transmission. Since there are inevitable manufacture errors, said mechanisms cannot remove gap in the double inner-meshed gears simultaneously, the seat back gap is therefore relatively large.